This invention relates to a process for alloying metals on supports for preparing a catalyst in which two or more metals are supported on the supports in the alloyed state. The process comprises adding a second metal onto the supports on which a first metal has been already supported and alloying the metals at a relatively low temperature.
Catalysts comprising carbon supports or inorganic oxide supports such as silica, and various catalyst metals, mainly a platinum metal, supported thereon have heretofore been employed as those for various chemical reactions and for the electrodes of fuel cells. A number of other catalysts which contain other metals such as nickel and chromium in addition to the platinum have been known for promoting the catalyst performance.
The catalyst performance of these catalysts depends on the degree of dispersion of the catalyst metals and the performance is promoted with the increase of the surface area of the catalyst if the same amount of the talyst is supported thereon. Although it is preferable to alloy the metals in the catalyst consisting of single supports and of a plurality of catalyst metals supported thereon, high degree of dispersion can not be obtained due to agglomeration of the metals if the alloying is performed at a high temperature. Once the metals are agglomerated, they can not be dispersed again for recovering the activity.
The present inventor is proposing a catalyst and a process for preparing the same in an application filed on the same day of the present application. The catalyst metals of the said catalyst seldom agglomerate with each other even if the catalyst is employed in a catalytic reaction at a high temperature, by carburizing a plurality of metals supported on carbon supports at high degree of dispersion to enhance the affinity between the supports and the metals.
However, even in this catalyst, no effect is obtained unless a plurality of the metals prior to the carburizing are highly dispersed, even if the movement of the metals from the fixed positions is prevented, because the activity before the movement is not high.
It has been heretofore required to develop a process which enables the highly dispersed metal supporting or the agglomeration of low degree when a plurality of metals are supported onto supports.